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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 575 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.511 + 356 =
  2. 2.276 + 442 =
  3. 3.237 + 278 =
  4. 4.964 − 453 =
  5. 5.149 + 119 =
  6. 6.470 − 307 =
  7. 7.392 + 407 =
  8. 8.240 + 525 =
  9. 9.620 − 195 =
  10. 10.651 + 235 =
  11. 11.788 − 237 =
  12. 12.313 + 407 =
  13. 13.578 + 686 =
  14. 14.785 − 574 =
  15. 15.810 − 678 =
  16. 16.911 − 454 =
  17. 17.918 − 325 =
  18. 18.429 − 317 =
  19. 19.577 − 296 =
  20. 20.171 + 262 =
  21. 21.607 + 611 =
  22. 22.209 + 613 =
  23. 23.277 + 171 =
  24. 24.187 + 654 =
  25. 25.442 + 161 =
  26. 26.909 − 574 =
  27. 27.153 + 512 =
  28. 28.185 + 665 =
  29. 29.712 − 194 =
  30. 30.437 − 275 =
  31. 31.714 − 339 =
  32. 32.682 − 298 =
  33. 33.507 − 328 =
  34. 34.578 − 271 =
  35. 35.232 + 286 =
  36. 36.136 + 668 =
  37. 37.412 − 226 =
  38. 38.123 + 273 =
  39. 39.605 − 327 =
  40. 40.533 + 123 =

Answer key

  1. 867
  2. 718
  3. 515
  4. 511
  5. 268
  6. 163
  7. 799
  8. 765
  9. 425
  10. 886
  11. 551
  12. 720
  13. 1264
  14. 211
  15. 132
  16. 457
  17. 593
  18. 112
  19. 281
  20. 433
  21. 1218
  22. 822
  23. 448
  24. 841
  25. 603
  26. 335
  27. 665
  28. 850
  29. 518
  30. 162
  31. 375
  32. 384
  33. 179
  34. 307
  35. 518
  36. 804
  37. 186
  38. 396
  39. 278
  40. 656

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